These things are fantastic when it comes to sound (relatively speaking for Bluetooth headphones) and battery life, especially considering how wonderfully tiny they are.
Obviously, they aren't going to compete with $500-$1000 wired headphones, but they still sound great, provided you can get a decent seal with the ear tips. They provide a variety of sizes and they are also compatible with Comply aftermarket ear tips. Making sure you get ear tips that seal inside your ear will make a huge difference in terms of sound quality.
They're great for their primary advertised functionality (working out) and I've found that even without the weird fin attachments (that you'll probably lose anyway), they stay in your ears very well.
But even better is that due to the great battery life, audio quality, and portability (it's literally two ear buds and a small cable between them), they're the best general-use Bluetooth headphones I've found. And I'm someone who has tried just about all of them out there.
I'm not really a fan of push-and-hold button interfaces, at least for the on/off functionality, but it's a minor issue.
The price is a bit higher than similar offerings (~$150 on Amazon as of 3/5/2014), but I still think these are worth it.
Additionally, these headphones are small enough that you can very easily lose them. Or they'll accidentally go through the wash. The latter has happened to me :( Again, that's not really the fault of the headphones, but it is something to watch out for.
If you're looking for headphones for everyday use while you're out and about, I think this is the very best pair out there due to sound quality, portability, and battery life.